This invention relates to new flame retardants for synthetic resins.
Special properties are required of flame retardants to be incorporated into thermoplastic synthetic resins. They must not be subject to thermal decomposition at the high processing temperatures used with the thermoplastic synthetic resins. Also, they must not bleed out of the thermoplastic synthetic resins into which they have been incorporated.
Various flame retardants, such as, for example, highly brominated biphenyls or highly brominated diphenyl ethers, tend to bleed out if they are exposed to extreme weathering conditions. These flame retardants tend to migrate to the surface when they are exposed, for example, while being incorporated into a synthetic resin, to the so-called tropic test, i.e., 14-days storage at 50.degree. C. and a relative atmospheric humidity of 100%. Not only do they thereby produce an undesirable surface coating but the intended flame-retarding effect is likewise reduced to a corresponding extent.
The problem thus exists to find suitable flame retardants for thermoplastic synthetic resins in whose use the above-mentioned undesirable properties do not occur.